An electromagnetic contactor includes an electromagnet that is powered through a control circuit so as to create an electromagnetic force actuating the movement of a moving part or core, which includes contacts designed to close or open an electric circuit.
The control signal for said electromagnet may be of the Pulse Width Modulation (PWM) type, with period T and pulse width T. The ratio T/T is noted as a cyclical ratio. It is known, for a given frequency of the pulse width modulation (PWM) signal and a given waveform, to vary the cyclical ratio T/T so as to modulate transferred energy.
In the situation, it has been noted that, when the control circuit is working in switching in this manner, parasites (harmonics) were generated, primarily by the switching at the charge both by conduction on the conductive power lines, and by radiation, this unfavorable situation being reinforced by the electric charge from the contactor essentially made up of a solenoid or an electromagnet.